J74/J74 Stereo Differential Kit

9 reviews

5499

Quantity

Pair of matched J74 (stereo) , for the differential amplifier found in the Aleph J and BA-1 gain stage.

Linear Systems JFETS, now available as a package for the differential amplifier found the the gain stage of the Aleph J and BA-1 front-end. These circuits use a matched pair of J74 P-channel fets for gain.

Each pair is matched to within 1.0mA Idss, ideal for a stereo Aleph J, BA-1 front end, and more

Each unit has 4 pieces in total, paired. The pairs are taped together in the package, please don't mix the pairs.

Limit of 1 unit per customer per monthdue to supply constraints. We want to ensure they all end up in the hands of builders who are going to use them for making projects, not hoarded or resold.If you need more than 1 for a particular build, please emailcontact@diyaudiostore.com with details of your build. Our goal is to see the most amps actually built and shared with the community as possible.

If you are building a F4, F5, F5T, F6, BA-3 or other amp with a complimentary (N-channel and P-channel pair) in the circuit, you do not want to use these transistors. What you are looking for is: Linear Systems Matched LSK170/LSJ74 Jfet Pairs.

Customer Reviews

Delivery speed, contact, shipping costs and packaging to someone on the other side of the world was outstanding. Going by other builds in the forum I know they'll work great. Thanks to the store for providing items like these to hobbyists!

it is just awesome to find genuine and already matched J74 transistors. Thank you very much diyAudio store to sell this critical parts, i will use these to build an Aleph J.

C

C.H.

Differential Kit LSJ74/LSJ74

Thanks for sending the differential pair kit of LSJ74's !
It was well packed - the two pairs in an antistatic bag, well taped together as matched pairs. The whole in a padded envelope, everything received in perfect condition.

Two points that might be bettered:

- the clear adhesive tape that was tying the legs of the matched pairs together left some sticky residue on the legs of the J-FETs. That might impair good contact when soldering.

- I did measure the Idss of the four J-FETs. One pair was perfectly matched (0,3% at 5V, 10V, 15V, 20V), the other much less so (around 2,4% difference in Idss at the four voltages, transconductance (gradient of the increase in Idss) was a bit different as well). What is your internal specification for a matched pair ?

Best regards,
Claas

Hi Claas!
Any stickytape residue will burn off when soldering. You can clean it off first, of course. Thanks for letting us know this was an issue for you. Perhaps we can address this in future packaging.
In regards to the matching tolerance, a 10% match is considered more than sufficient for the purpose, which means matches you got were close to, and the other literally, perfect.
Thanks for your feedback :)